Lathe-dog.



No. 715,900. Pate nted Dec. [6, I902. T. c. THOMPSON.

LATHE DOG.

Application filed Aug. 7, 1902.)

(No Model.)

UNITED STATES,

" ATEN'T rrrcn.

THOMAS C. THOMPSON, OF CINCINNATI, OHIO, ASSIGNOR OF TWO-THIRDS TO MAURICE E. POLLAK,'OF CINCINNATI, OHIO, AND FRED NORRIS, OF

OARTHAGE, OHIO.

' L-ATHE-DOGI SPECIFICATION forming part of Letters Patent No. 715,900, dated December 16, 1902.

Application filed August 7,1902. Serial No. 118,738. (No model) To ctZZ whom it may concern.-

Be it known that I, THOMAS C. THOMPSON, a citizen of the United States, residing at Cincinnati, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Lathe Dogs, of which the following is a specification.

My invention relates to lathe-dogs; and the improvement will be readily understood from the following description, taken in connection with the accompanying drawings, in which Figure 1 is a perspective view of my im proved device shown in connection with the face-plate of a lathe and a shaft, broken away, to which the dog is clutched. Fig. 2 is a plan View of my improved device with the outer end of the lever broken away. Fig. 3 is a bottom view of the same. Fig. 4 is a side elevation of my improved device with shafts of dilferent diameters indicated in dotted lines and the lever indicated in dotted lines in assumed position. Fig. 5 is a detail in perspective, partly broken away, showing the manner of seating and securing the shoe in the stock; and Fig. 6 is a side elevation, partly in section, of the engaging pin, showthe stock, and a lever 3 is pivoted on a pin 4 The stock also between the stock and lug. has sideward extensions 5 5 on the same side as the lug. Seats 66, describingthe arc of a circle, are located in the stock and extensions, with the axes of the circles parallel with the axis of the stock. These seats extend more than the half of the circle, being open toward the axis of the stock, forming grooves in the inner face of the stock. Shoes 7 7 are located within the seats,with the seating-faces forming rolling shoes;

of the shoes coinciding with the seats, thus The shoes have engaging faces 8, arranged on the arc of a circle of greater diameter than the diameter of the circle of the seating-face of the shoe. These engaging faces are provided with teeth. The seats 6 being larger than the half of a circle permit the shoes to he slid into the seats from their ends, but prevent their being removed radially. In order to secure the shoes in the seats longitudinally,each shoe is provided with a groove 10,eXt-ending partway around its side, as indicated in dotted lines in Fig. 4 and in Fig. 5. A pin 11 takes through an aperture in the stock and into the groove and is suitably secured to the stock by being riveted therein. The inner end 12 of the lever 3 is provided with teeth 13 and is movable toward and from the axis of the stock for thepurpose of clamping the object to be turned between the lever and the shoes.

In operation if it isdesired to clamp the object to be turned in the lathe the lathe-dog is loosely placed about the object and an engaging pin D secured to the face-plate in suitable position to strike the outer end 15 of the lever, whereupon the lever turns upon its pivot and thrusts the inner end 12 of the lever toward the work engaging therewith. As soon as the inner end of the lever engages with the work resistance is caused to the movement of the outer end of the lever, which causes the inner end ofthe lever to be *more forcibly pressedagainst the work, simultaneously pressing the work against the teeth of the engaging faces of the shoes 7. The

arcs in which these engaging faces are located with relation to the axes of the shoes is such that if resistance by the work is brought against the shoes it will cause the shoes to roll, and the engaging faces of the shoes will move toward the axis of the stock, thereby crowding against the work and aiding in holding it rigidly to the face-plate. In my improved construction the greater resistance to the turning of the work the greater will be the pressure by the dog, so that a firnl gripping of work by the dog is always assured.

The engaging face of the inner end of the lever in which the teeth 13 are located may assume the form shown in Fig. 4, in which that part of the engaging face nearest the pivot of the lever is curved outwardly from the axis of the stock and that part toward the outer end of the engaging face is involutely curved, so as to bring the largest engaging surface against the larger bodies of work and the maximum engaging surface against the smaller bodies. In Fig. 4 various diameters of work are indicated by dotted lines and the engaging face of the inner end of the lever indicated in dotted lines as engaging a small piece of work to indicate the range of the dog without adjustment. The engaging face of the lever is preferably vertically disposed above the engaging faces of the shoes, as shown in the drawings.

The engaging pin D may assume the form shown in Fig. 6, in which 17 represents the ordinary slot of the face-plate, 18 a T-bolt, and 19 a cap having a square head 20, the lips 21 of the slot 17 being clamped between the head of the T-bolt and the cap in suitable position in the length of the slot for proper engagement with the outer end of the lever.

The position of the lathe-dog with relation to the face-plate may be reversed if motion is imparted to the face-plate in the reverse direction.

It will be noticed that with my improved construction of the inner end of the lever I am permitted to give the inner end of the lever a long engaging face for engaging stock of a wide range of diameters without adjustment of parts. Thus in Fig. 4 of the drawings the largest dotted circle 22 indicates a shaft of six inches diameter, the next smaller 23 a shaft five inches in diameter, the next smaller 2% a shaft four inches in diameter, and the smallest circle 25 a shaft three inches in diameter, indicating a wide range of my improved dog, as demonstrated by actual prac-' tice, without adjustment of parts.

What I claim to be new, and desire to secure by Letters Patent, is

1. In a lathe-dog, the combination of a stock, a lever pivoted thereto, having an engaging face at its inner end arranged to swing within the stock past the axis of the stock, an engaging face for the inner end of the le- Ver, and opposing rolling shoes rollingly mounted in the stock, substantially as described.

2. In a lathe-dog, the combination with a face-plate, and a pin secured thereto, of a stock, a lever pivoted to the stock having an engaging face at its inner end arranged to move within the stock past the axis of the stock, opposing grooves in the inner face of the stock having seats curved in the arc of a circle and occupying more than a semicircle, shoes having coinciding seating-faces rolling in the seats and guided therebyin rolling, and constructed and arranged for permitting the shoes to be slid axially into the seats and prevented from radial movement by the walls of the seats, substantially as described.

3. In a lathe-dog, the combination of a stock, a lever pivoted thereto having an inner end arranged to move within the stock past its center, an engaging face for said inner end having a curve outward from said center near the pivot of the lever, said outward curve merging into an involute curve toward the free end of the engaging face, opposing grooves in the inner face of the stock having seats curved in the arc of a circle and occupying more than a semicircle, shoes having coinciding seating-faces rolling in the seats and guided therebyin rolling, and constructed and arranged for permitting the shoes to he slid axially into the seats and prevented from radial movement bythe walls of the seats, substantially as described.

4. In a lathe-dog, the combination of a stock, a lever pivoted thereto, an engaging face for the inner end of the lever, opposing grooves in the inner face of the stock having seats curved in the arc of a circle and occupying more than a semicircle, shoes having coinciding seating-faces rolling in the seats and guided therebyin rolling, and constructed and arranged for permitting the shoes to be slid axially into the seats and prevented from radial movement by the walls of the seats, substantially as described.

In testimony whereof I have signed my name hereto in the presence of two subscribing witnesses.

THOMAS C. THOMPSON.

Witnesses:

MAURICE E. POLLAK, A. F. HERBSLEB. 

